Abstract: Background: Successful highly active antiretroviral therapy (HAART) regimens have resulted in substantial improvements in the systemic health of HIV infected persons and increased survival times. Despite increased systemic health, the prevalence of minor HIV-associated cognitive impairment appears to be rising with increased longevity, and it remains to be seen what functional outcomes will result from these improvements. Cognitive impairment can dramatically impact functional ability and day-to-day productivity. We assessed the relationship of quality of life (QOL) and neuropsychological functioning with successful HAART treatment. Methods: In a prospective longitudinal study, subjects were evaluated before instituting HAART (naïve) or before changing HAART regimens because current therapy failed to maintain suppression of plasma viral load (treatment failure). Subjects underwent detailed neuropsychological and neurological examinations, as well as psychological evaluation sensitive to possible confounds. Re-evaluation was performed six months after institution of the new HAART regimen and/or if plasma viral load indicated treatment failure. At each evaluation, subjects underwent ultrasensitive HIV RNA quantitative evaluation in both plasma and cerebrospinal fluid. Results: HAART successes performed better than failures on measures exploring speed of mental processing (p < .02). HAART failure was significantly associated with increased self-reports of physical health complaints (p < .01) and substance abuse (p < .01). An interesting trend emerged, in which HAART failures endorsed greater levels of psychological and cognitive complaints (p = .06). Analysis between neuropsychological measures and QOL scores revealed significant correlation between QOL Total and processing speed (p < .05), as well as flexibility (p < .05). Conclusion: Our study investigated the relationship between HIV-associated neurocognitive impairment and quality of life. HAART failures experienced slower psychomotor processing, and had increased self-reports of physical health complaints and substance abuse. Contrariwise, HAART successes experienced improved mental processing, demonstrating the impact of successful treatment on functioning. With increasing life expectancy for those who are HIV seropositive, it is important to measure cognitive functioning in relation to the actual QOL these individuals report. The study results have implications for the optimal management of HIV-infected persons. Specific support or intervention may be beneficial for those who have failed HAART in order to decrease substance abuse and increase overall physical health.